Recently, as application processors (AP) of smartphones have become thinner, the necessity for a thin film capacitor, thinner than a multilayer ceramic capacitor (MLCC), has increased.
The thin film capacitor may be developed at a thin thickness using a thin film technology, but has a large limitation in the number of dielectric layers that may be stacked as compared to the MLCC, such that it is difficult to implement high capacitance.
A thin film deposited by a sol-gel method, a sputtering method, a chemical vapor deposition (CVD) method, a pulsed laser deposition (PLD) method, and the like, which are thin film technologies, may have excellent characteristics depending on deposition conditions, but in the case of stacking a plurality of layers, since properties of a lower electrode or a layer serving as a seed layer dominate characteristics of a dielectric layer deposited thereon, generally, as the number of layers is increased, characteristics of the dielectric layer may deteriorate rapidly.
In detail, the reason for this deterioration is that, at the time of manufacturing a capacitor, a flat film may be suitably deposited on a lower electrode, but in the case of depositing a dielectric layer on the lower electrode and depositing an electrode layer on the dielectric layer, the roughness of the electrode layer may be significantly increased due to dielectric grains of the dielectric layer, and a rough surface of the dielectric layer is substantially reflected in an upper electrode.
In a case of stacking the dielectric layer on the electrode layer having a rough surface, since the dielectric layer is deposited on a seed layer that is not flat, crystallinity of the dielectric layer may be significantly deteriorated, and the roughness may also be significantly increased.
When the stacking as described above is repeatedly performed, the dielectric layer may include non-uniformly formed grains, permittivity may be deteriorated, and leakage characteristics through a grain boundary may be deteriorated, such that it may be difficult to manufacture the capacitor by stacking the electrode layers and the dielectric layers.
Therefore, a thin film capacitor in which characteristics of a dielectric layer may be secured and a plurality of electrode layers and dielectric layers are stacked should be developed.